Circuit boards and IC substrates produced for the optoelectronics and semiconductor industries are trending toward high-speed, high-density, intensive, and high integration because of the rise of the “Cloud”, “Internet” and “Internet of things”, enhancements of 4G and 5G communication technologies, and improvement in display technologies. The required properties of the circuit boards and the IC substrates of the future are not only low dielectric constant and high insulation, but also low dielectric loss and high thermal conductivity. For example, the copper foil substrate in a circuit board is concisely represented as copper foil/dielectric layer/copper foil, and the middle dielectric layer is usually composed of resin, glass fiber cloth, or insulation paper with low thermal conductivity. Therefore, the copper foil substrate has a poor thermal conductivity. In general, a large amount of thermally conductive powder is often added to the dielectric layer to increase the thermal conductivity of the dielectric layer. However, the resin between the thermally conductive powder is not thermally conductive, such that the thermally conductive effect of the thermally conductive powder dispersed in the resin is limited.
A novel thermally conductive resin collocated with the thermally conductive powder is called for to overcome the above issue and increase the thermal conductivity of the dielectric layer between the copper foils.